FIG. 1.

Effects of LPS-27 and LPS-37 isolated from Y. pestis on the stimulation of mouse macrophage RAW264.7 cells and human macrophage U937 cells. (A) Mouse RAW264.7 cells were stimulated with LPS-27, LPS-37, and reference Salmonella LPS at the indicated doses. (B) Human U937 cells were stimulated as described for panel A. The cytokine levels in the culture supernatant at 6 h after stimulation were determined by ELISA. The data are presented as the means ± standard errors of triplicate samples, and a representative result from three independent experiments is shown. h, human; m, mouse.